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26 Sep 2011

timnolan.com writes:

This is a project I did a couple of years back for a business friend of mine to automatically log all his phone calls into his computer. The hardware (pictured above) uses an microprocessor to monitor the phone calls (incoming and outgoing) and send the data out the serial port to be read by the computer.

The hardware is controlled by an Atmel AVR ATmega32 microprocessor. The processor uses optoisolators to see if the phone is off-hook and to check if the incoming line is ringing. If the phone is off-hook a DTMF decoding chip CM8870CP is used to decode the number that is dialed. If it is an incoming call an FSK decoding chip XR2211 is used to decode the Caller ID data.

Phone Call Logging Project - [Link]

26 Sep 2011

timnolan.com writes:

For the last year I’ve been working on a prototype for a Solar Inverter that can be Grid Intertied. A solar inverter takes the 12V DC (or other voltages) from the solar panels and converts it to 120V AC which is the power that most of your household appliances use. A Grid-Intertied inverter allows you to feed that power back into power grid (your house power) to help power your household appliances.

My goal was to design a small inverter, about 100W, that could be used with one solar panel and could be grid intertied. My second prototype (pictured above) has achieved these design goals. So on these web pages I’m going to document the design of the hardware and the software of my solar inverter. I’m releasing these designs to public without restrictions. All I ask is that if you use any of my design that you credit me and add a link back to this website. I hope these designs will help further the work of other people in this area.

Solar Grid-Intertie Inverter - [Link]

26 Sep 2011

timnolan.com writes:

To understand why the PPT can increase the efficiency of your solar power charging system a closer at the electrical characteristics of a solar panel is necessary. Solar panels convert photons from the sun striking their surfaces into electricity of a characteristic voltage and current. The solar panel’s electrical output can be plotted on a graph of voltage vs. current: an IV curve. I represents the current in amps and V represents the voltage in volts. The resulting line on the graph shows the current output of the panel for each voltage at a specific light level and temperature. (Fig. 2) The current is constant until reaching the higher voltages, when it falls off rapidly. This IV curve is applicable to the electrical output of all solar panels.

Arduino Peak Power Tracker Solar Charger - [Link]

26 Sep 2011

Interesting article from the Bad Astronomy Blog at Discovery.com: [via]

So the web is buzzing right now over news that scientists have detected some subatomic particles moving faster than the speed of light.

Yeah, well, not so fast. Let’s think about this for a sec.

First, what happened is that they create these particles, called neutrinos, at CERN in Geneva. Neutrinos don’t interact with normal matter well, so they can pass right through the Earth as if it isn’t there. In a fraction of a second, some of them enter a detector called OPERA in Italy where they are recorded (pictured here). If you divide the distance between those two points by the time it takes for the neutrinos to travel, you get their speed.

And when the scientists did that, they find the neutrinos get to Italy about 60 nanoseconds faster than a photon would.

The thing to do is to look at where this claim might have gone awry. First, the timing is interesting. They claim a measuring accuracy of 10 nanoseconds, so 60 ns would be pretty significant. However, my first thought is that light travels about 30 centimeters in 1 ns, so they need to know the distance between the source and the detector to an accuracy of 3 meters. If they are off by 20 meters, then we’re done; that would explain the difference entirely. I suppose this depends on how they measured the distance and the speed of the particles, too. However, they haven’t published a paper on this just yet, so that’ll have to wait.

Also, as pointed out in a Science Magazine article, knowing the exact moment the neutrinos are created isn’t easy either. Mind you, 60 nanoseconds is 0.00000006 seconds, so they need a pretty good clock here. That page also says they used GPS to determine the distance, which could be off a bit.

Why the Faster-than-Light Neutrino Experiment May Be Wrong - [Link]

26 Sep 2011

Block Diagram (SBD) – Tablet – TI.com. [via]

Texas Instruments (TI) offers a variety of semiconductor solutions for tablets and eBooks. The OMAPTM processor shown in the system diagram perfectly balances power and performance to give designers and end users an optimal multimedia solution. Also represented is an extensive array of solutions for tablets and eBooks that support wireless connectivity, video, audio and power management. The selection guide on the following page is a sampling of TI devices available to streamline your design process.

Tablet and eBook System Diagram from TI - [Link]

26 Sep 2011

Open Hardware Needs a SourceForge of its Own by Mach 30 @ Kickstarter.

The problem
If you want to host an open source hardware project today, you have to cobble together wikis, forums, online polls, blogs, and online file storage to share your materials. Then you have to send the link (or links) to your “system” to the people you already know who might be interested in participating. For a person who just wants to start designing and building cool stuff all that pre-work is a giant pain in the you-know-what.
So is it any wonder that most makers interested in open sourcing their designs tend to skip that step, do all the work themselves and then just release the final designs on the web when they get around to it?

There has to be a better way.

In order for open source hardware to become as prevelant and infulential in the hardware community as FOSS is in the software community we need a way to integrate the required services into a single system, as well as provide a destination for users looking for open source hardware projects to build or to extend to get involved in the community.

Enter Open Design Engine.

The solution
If it takes a forge to develop open source software, then you need an engine to develop open source hardware. Introducing Open Design Engine (ODE). ODE is a web based engineering project management system created to facilitate the design and development of openly licensed hardware projects. ODE provides a critical service to the growing open source hardware community, similar to the role Source Forge played in the early growth of open source software.

ODE is based on the open source software Redmine and is licensed under the GNU General Public License v2 (GPL). ODE is being distributed in a similar manner to WordPress. Which means there will be a version available for download that users can install on their own servers (like http://wordpress.org) and a hosted version where users can register accounts and host projects (like http://wordpress.com).

Version 0.1 of the site is up and running at https://opendesignengine.net, but before user accounts can be made available to the public, V0.2 must be completed.

Open Hardware Needs a SourceForge of its Own by Mach 30 @ Kickstarter - [Link]

26 Sep 2011

Jeri shows the basic construction of solenoid actuators and demonstrates the relationship between strength and hold power relative to current flow in the coil. [via]

Solenoid Basics - [Link]

26 Sep 2011

adafruit.com writes: [via]

In the spirit of the slow, automated writing machine in Kafka’s “In the Penal Colony”, but channeled through laser-cut plastic, hobby servos and ink, “The Bureaucrat” was at the NYC Resistor table at MakerFaire, stamping the date on hackerspace passports.

“The Bureaucrat” — A Hackerspace Passport Date-Stamping Machine - [Link]

23 Sep 2011

The SmartPulse™ family of DECT-based wireless sensors and base station devices from Dialog Semiconductor facilitate the creation of wireless sensor networks for home automation, security, health care and energy monitoring applications. DECT is an established technology that provides whole-house coverage, and SmartPulse with DECT ULE builds on this legacy. Its simple star networks can be used for a variety of home automation applications.

Systems running SmartPulse sensors can self-configure with a home’s DECT / DECT ULE hub or internet gateway, allowing connected systems to be managed over the web using a smartphone, laptop or tablet PC. Additionally, the sleep mode of DECT ULE enables a wide range of new wireless consumer products that run for up to 10 years on a single AAA battery pack. [via]

Wireless home automation devices build on DECT technology - [Link]

23 Sep 2011

Engineers at the University of California, Berkeley, have shown that it is possible to reduce the minimum voltage necessary to store charge in a capacitor, an achievement that could reduce the power draw and heat generation of today’s electronics. Shown is a rendition of an experimental stack made with a layer of lead zirconate titanate, a ferroelectric material. UC Berkeley researchers showed that this configuration could amplify the charge in the layer of strontium titanate, an electrical insulator, for a given voltage, a phenomenon known as negative capacitance.

“Just like a Formula One car, the faster you run your computer, the hotter it gets. So the key to having a fast microprocessor is to make its building block, the transistor, more energy efficient,” said Asif Khan, UC Berkeley graduate student in electrical engineering and computer sciences. “Unfortunately, a transistor’s power supply voltage, analogous to a car’s fuel, has been stuck at 1 volt for about 10 years due to the fundamental physics of its operation. Transistors have not become as ‘fuel-efficient’ as they need to be to keep up with the market’s thirst for more computing speed, resulting in a cumulative and unsustainable increase in the power draw of microprocessors. We think we can change that.” [via]

Negative capacitance – one day soon - [Link]





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